The present invention relates to an apparatus for driving a medical appliance such as an artificial heart or balloon pump in the main artery, more particularly to a fluid driving apparatus for regularly changing the fluid pressure.
A conventional driving apparatus for driving a medical appliance is shown in Japanese Kokai application No. 58(1983)-169460. When driving a medical pump such as an artificial heart pump, a positive pressure and a negative pressure are applied to a driving portion of the heart pump periodically in accordance with the pulsation of a natural heart so that the heart pump assists blood circulation. In order to drive a medical appliance in this way, the driving apparatus has a positive pressure generating device which generates a constant positive pressure, a negative pressure generating device which generates a constant negative pressure and a pressure changing device which changes the positive and negative pressures from the positive and negative pressure generating devices periodically. It is required for an artificial heart pump to change pressures quickly, from positive pressure to negative pressure and from negative pressure to positive pressure. Thus conventional driving apparatuses are designed to keep generating pressures as constant as possible. Generally, a positive pressure from the positive pressure generating device goes down when the positive pressure is applied to the heart pump and a negative pressure from negative pressure generating device goes down when the negative pressure is applied to the heart pump. To prevent these pressure drops, the positive and negative pressure generating devices are provided with accumulators for accumulating pressure reserves. Though accumulators may prevent such pressure drops, it is necessary to provide fairly big accumulators to prevent the pressure drops. As a result, the driving apparatus becomes extremely large and hard to move.